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          <th colspan="3" align="center">DB_ENV-&gt;set_tx_max()</th>
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            <h2 class="title" style="clear: both"><a id="envset_tx_max"></a>DB_ENV-&gt;set_tx_max()</h2>
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      <pre class="programlisting">#include &lt;db.h&gt;

int
DB_ENV-&gt;set_tx_max(DB_ENV *dbenv, u_int32_t max);  </pre>
      <p>
         Configure the Berkeley DB database environment to support at least
         <span class="bold"><strong>max</strong></span> active transactions.  This value
         bounds the size of the memory allocated for transactions.  Child
         transactions are counted as active until they either commit or abort.
    </p>
      <p>
         Transactions that update multiversion databases are not freed until
         the last page version that the transaction created is flushed from
         cache. This means that applications using multi-version concurrency
         control may need a transaction for each page in cache, in the extreme
         case.
    </p>
      <p>
         When all of the memory available in the database environment for
         transactions is in use, calls to 
         <a class="xref" href="txnbegin.html" title="DB_ENV-&gt;txn_begin()">DB_ENV-&gt;txn_begin()</a>  will fail
         (until some active transactions complete).  If 
         <code class="classname">DB_ENV-&gt;set_tx_max()</code> is never called,
         the database environment is configured to support at least 100
         active transactions.
    </p>
      <p>
         The database environment's number of active transactions may also
         be configured using the environment's <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file. The syntax
         of the entry in that file is a single line with the string
         "set_tx_max", one or more whitespace characters, and the number of
         transactions. Because the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file is read when the
         database environment is opened, it will silently overrule
         configuration done before that time.
    </p>
      <p>
         The <code class="methodname">DB_ENV-&gt;set_tx_max()</code> method configures
         a database environment, not only operations performed using the
         specified <a class="link" href="env.html" title="Chapter 5.  The DB_ENV Handle">DB_ENV</a>  handle.
    </p>
      <p>
         The <code class="methodname">DB_ENV-&gt;set_tx_max()</code> method may not be called after the 
         <a class="xref" href="envopen.html" title="DB_ENV-&gt;open()">DB_ENV-&gt;open()</a>  method is called.
         If the database environment already exists when 
         <a class="xref" href="envopen.html" title="DB_ENV-&gt;open()">DB_ENV-&gt;open()</a>  is called, the
         information specified to <code class="methodname">DB_ENV-&gt;set_tx_max()</code> will be ignored.
    </p>
      <p>
         The <code class="methodname">DB_ENV-&gt;set_tx_max()</code> <span>
            <span>
                  method returns a non-zero error value on failure and 0 on success.
            </span>
            
        </span>
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      <div class="sect2" lang="en" xml:lang="en">
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              <h3 class="title"><a id="idp54766712"></a>Parameters</h3>
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        <div class="sect3" lang="en" xml:lang="en">
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                <h4 class="title"><a id="idp54766064"></a>max</h4>
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          <p>
                          The <span class="bold"><strong>max</strong></span> parameter configures the
                          minimum number of simultaneously active transactions supported by
                          Berkeley DB database environment.
                     </p>
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      <div class="sect2" lang="en" xml:lang="en">
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              <h3 class="title"><a id="idp54769704"></a>Errors</h3>
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        <p>
                         The <code class="methodname">DB_ENV-&gt;set_tx_max()</code> <span>
            <span>
                 method may fail and return one of the following non-zero errors:
            </span>
            
        </span>
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        <div class="sect3" lang="en" xml:lang="en">
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                <h4 class="title"><a id="idp54777456"></a>EINVAL</h4>
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                If the method was called after <a class="xref" href="envopen.html" title="DB_ENV-&gt;open()">DB_ENV-&gt;open()</a> 
                was called; or if an invalid flag value or parameter was specified.
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              <h3 class="title"><a id="idp54765848"></a>Class</h3>
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        <p>
                    <a class="link" href="env.html" title="Chapter 5.  The DB_ENV Handle">DB_ENV</a>, 
                    <a class="link" href="txn.html" title="Chapter 12.  The DB_TXN Handle">DB_TXN</a> 
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      <div class="sect2" lang="en" xml:lang="en">
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              <h3 class="title"><a id="idp54779688"></a>See Also</h3>
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        <p>
                     <a class="xref" href="txn.html#txnlist" title="Transaction Subsystem and Related Methods">Transaction Subsystem and Related Methods</a> 
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